Transduction (genetics)

Definition: In genetics, transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. It is a mechanism of horizontal gene transfer, meaning that genetic material is transferred between organisms other than by the "vertical" transmission of DNA from parent to offspring. This contrasts with transformation (the uptake of free DNA from the environment) and conjugation (direct transfer of DNA between two bacterial cells).

Types of Transduction:

• Generalized Transduction: This occurs when a bacteriophage (a virus that infects bacteria) packages fragments of the host bacterial DNA during the lytic cycle. These fragments can then be transferred to a new host bacterium upon infection. Any portion of the bacterial genome can be transferred via generalized transduction, making it a useful tool for bacterial genetics research.

• Specialized Transduction: This type of transduction involves temperate bacteriophages (phages that can integrate their DNA into the host's genome). When the phage exits the lysogenic state (where the phage DNA is integrated into the bacterial chromosome), it may accidentally excise (cut out) a small piece of adjacent bacterial DNA along with its own genome. This bacterial DNA is then packaged into new phage particles and transferred to other bacteria. Because only genes adjacent to the phage's integration site can be transduced, specialized transduction is more specific than generalized transduction.

Mechanism:

The detailed mechanism varies slightly between generalized and specialized transduction. However, both processes involve the packaging of bacterial DNA into phage capsids, followed by the infection of a new bacterial cell with this packaged DNA. Once inside the new host, the transferred DNA may recombine with the host genome, leading to a change in the host's genotype and potentially its phenotype. If the transferred DNA carries genes conferring advantageous traits, this can contribute to the evolution of bacterial populations.

Significance:

Transduction plays a significant role in bacterial evolution, allowing for the spread of antibiotic resistance genes and other virulence factors. It's also a valuable tool in molecular biology, used in various genetic engineering techniques. Understanding transduction is critical in fields such as microbiology, infectious disease research, and biotechnology.

Related Terms:

• Bacteriophage
• Lytic Cycle
• Lysogenic Cycle
• Horizontal Gene Transfer
• Transformation
• Conjugation
• Recombination
• Genetic Engineering